!(function(doc, win) {
        var docEle = doc.documentElement,//获取html元素
            event = "onorientationchange" in window ? "orientationchange" : "resize",//判断是屏幕旋转还是resize;
            fn = function() {
                var width = docEle.clientWidth;
                width && (docEle.style.fontSize = 50 * (width / 375) + "px");//设置html的fontSize，随着event的改变而改变。
            };
        win.addEventListener(event, fn, false);
        doc.addEventListener("DOMContentLoaded", fn, false);
}(document, window));
